METHOD OF CLEANING FLY ASH GRAPHITE (VERSIONS) Russian patent published in 2021 - IPC C01B32/215 

FIELD: chemical industry.

SUBSTANCE: invention can be used in production of tubular heaters, structural materials for nuclear power engineering and heat engineering, crucibles for melting of metals and multicomponent glass, as well as in production of colloidal graphite, graphite oxide and expanded graphite. According to the first version, the ash graphite is mixed with an aqueous solution of ammonium bifluoride. Obtained mixture is thermally treated once at 60–70 °C for 4–6 hours. Product is cooled to room temperature and treated with 2 % ammonium bifluoride solution, then, filtering with simultaneous washing directly on filter with new portion of 2 % ammonium bifluoride solution. Filtered and washed product is mixed with ammonium sulphate solution. Mixture is calcinated at 350–370 °C for 4.0–4.5 hours. After cooling to room temperature, the calcined product is pulverized in water, filtered and simultaneously washed with water and directed for drying. According to the second version, the ash graphite is first mixed with an aqueous solution of ammonium sulphate. Obtained mixture is annealed by raising temperature at rate of 2.0–2.5 deg/min to 350–370 °C with holding at the achieved temperature for 4.0–4.5 hours. Obtained product is cooled to room temperature and ground in water at T:L=1:10, settled for 15–20 minutes and the precipitate is filtered off with simultaneous washing with water at T:L =1:10. Washed and filtered precipitate is mixed with ammonium bifluoride dissolved in water. Produced dough-like mass is thermally treated at 60–70 °C for 4–6 hours. Product is cooled and treated with 2 % ammonium bifluoride solution. Precipitate is filtered out, washed directly on filter with 2 % ammonium bifluoride solution and directed for drying.

EFFECT: technical result is simplification of method of cleaning of ash graphite and its hardware.

7 cl, 4 ex